21 Search Results for "Stiller, Sebastian"

Volume

OASIcs, Volume 33

13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems

ATMOS 2013, September 5, 2013, Sophia Antipolis, France

Editors: Daniele Frigioni and Sebastian Stiller

Document
DOI: 10.4230/OASIcs.ATMOS.2018.5
Fast Robust Shortest Path Computations

Authors: Christoph Hansknecht, Alexander Richter, and Sebastian Stiller

Published in: OASIcs, Volume 65, 18th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2018)

Abstract
We develop a fast method to compute an optimal robust shortest path in large networks like road networks, a fundamental problem in traffic and logistics under uncertainty. In the robust shortest path problem we are given an s-t-graph D(V,A) and for each arc a nominal length c(a) and a maximal increase d(a) of its length. We consider all scenarios in which for the increased lengths c(a) + bar{d}(a) we have bar{d}(a) <= d(a) and sum_{a in A} (bar{d}(a)/d(a)) <= Gamma. Each path is measured by the length in its worst-case scenario. A classic result [Bertsimas and Sim, 2003] minimizes this path length by solving (|A| + 1)-many shortest path problems. Easily, (|A| + 1) can be replaced by |Theta|, where Theta is the set of all different values d(a) and 0. Still, the approach remains impractical for large graphs. Using the monotonicity of a part of the objective we devise a Divide and Conquer method to evaluate significantly fewer values of Theta. This methods generalizes to binary linear robust problems. Specifically for shortest paths we derive a lower bound to speed-up the Divide and Conquer of Theta. The bound is based on carefully using previous shortest path computations. We combine the approach with non-preprocessing based acceleration techniques for Dijkstra adapted to the robust case. In a computational study we document the value of different accelerations tried in the algorithm engineering process. We also give an approximation scheme for the robust shortest path problem which computes a (1 + epsilon)-approximate solution requiring O(log(d^ / (1 + epsilon))) computations of the nominal problem where d^ := max d(A) / min (d(A)\{0}).
Cite as

Christoph Hansknecht, Alexander Richter, and Sebastian Stiller. Fast Robust Shortest Path Computations. In 18th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2018). Open Access Series in Informatics (OASIcs), Volume 65, pp. 5:1-5:21, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2018)

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@InProceedings{hansknecht_et_al:OASIcs.ATMOS.2018.5,
  author =	{Hansknecht, Christoph and Richter, Alexander and Stiller, Sebastian},
  title =	{{Fast Robust Shortest Path Computations}},
  booktitle =	{18th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2018)},
  pages =	{5:1--5:21},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-096-5},
  ISSN =	{2190-6807},
  year =	{2018},
  volume =	{65},
  editor =	{Bornd\"{o}rfer, Ralf and Storandt, Sabine},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2018.5},
  URN =		{urn:nbn:de:0030-drops-97100},
  doi =		{10.4230/OASIcs.ATMOS.2018.5},
  annote =	{Keywords: Graph Algorithms, Shortest Paths, Robust Optimization}
}
Document
DOI: 10.4230/LITES-v003-i001-a004
Optimal Scheduling of Periodic Gang Tasks

Authors: Joël Goossens and Pascal Richard

Published in: LITES, Volume 3, Issue 1 (2016). Leibniz Transactions on Embedded Systems, Volume 3, Issue 1

Abstract
The gang scheduling of parallel implicit-deadline periodic task systems upon identical multiprocessor platforms is considered. In this scheduling problem, parallel tasks use several processors simultaneously. We propose two DPFAIR (deadline partitioning) algorithms that schedule all jobs in every interval of time delimited by two subsequent deadlines. These algorithms define a static schedule pattern that is stretched at run-time in every interval of the DPFAIR schedule. The first algorithm is based on linear programming and is the first one to be proved  optimal for the considered gang scheduling problem. Furthermore, it runs in polynomial time for a fixed number m of processors and an efficient implementation is fully detailed. The second algorithm is an approximation algorithm based on a fixed-priority rule that is competitive under resource augmentation analysis in order to compute an optimal schedule pattern. Precisely, its speedup factor is bounded by (2-1/m). Both algorithms are also evaluated through intensive numerical experiments.
Cite as

Joël Goossens and Pascal Richard. Optimal Scheduling of Periodic Gang Tasks. In LITES, Volume 3, Issue 1 (2016). Leibniz Transactions on Embedded Systems, Volume 3, Issue 1, pp. 04:1-04:18, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2016)

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@Article{goossens_et_al:LITES-v003-i001-a004,
  author =	{Goossens, Jo\"{e}l and Richard, Pascal},
  title =	{{Optimal Scheduling of Periodic Gang Tasks}},
  booktitle =	{LITES, Volume 3, Issue 1 (2016)},
  pages =	{04:1--04:18},
  journal =	{Leibniz Transactions on Embedded Systems},
  ISSN =	{2199-2002},
  year =	{2016},
  volume =	{3},
  number =	{1},
  editor =	{Goossens, Jo\"{e}l and Richard, Pascal},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LITES-v003-i001-a004},
  doi =		{10.4230/LITES-v003-i001-a004},
  annote =	{Keywords: Real-time systems, Scheduling, Parallel tasks}
}
Document
DOI: 10.4230/LITES-v001-i002-a001
Blocking Optimality in Distributed Real-Time Locking Protocols

Authors: Björn Bernhard Brandenburg

Published in: LITES, Volume 1, Issue 2 (2014). Leibniz Transactions on Embedded Systems, Volume 1, Issue 2

Abstract
Lower and upper bounds on the maximum priority inversion blocking (pi-blocking) that is generally unavoidable in distributed multiprocessor real-time locking protocols (where resources may be accessed only from specific synchronization processors) are established. Prior work on suspension-based shared-memory multiprocessor locking protocols (which require resources to be accessible from all processors) has established asymptotically tight bounds of Ω(m) and Ω(n) maximum pi-blocking under suspension-oblivious and suspension-aware analysis, respectively, where m denotes the total number of processors and n denotes the number of tasks. In this paper, it is shown that, in the case of distributed semaphore protocols, there exist two different task allocation scenarios that give rise to distinct lower bounds. In the case of co-hosted task allocation, where application tasks may also be assigned to synchronization processors (i.e., processors hosting critical sections), Ω(Φ · n) maximum pi-blocking is unavoidable for some tasks under any locking protocol under both suspension-aware and suspension-oblivious schedulability analysis, where Φ denotes the ratio of the maximum response time to the shortest period. In contrast, in the case of disjoint task allocation (i.e., if application tasks may not be assigned to synchronization processors), only Ω(m) and Ω(n) maximum pi-blocking is fundamentally unavoidable under suspension-oblivious and suspension-aware analysis, respectively, as in the shared-memory case. These bounds are shown to be asymptotically tight with the construction of two new distributed real-time locking protocols that ensure O(m) and O(n) maximum pi-blocking under suspension-oblivious and suspension-aware analysis, respectively.
Cite as

Björn Bernhard Brandenburg. Blocking Optimality in Distributed Real-Time Locking Protocols. In LITES, Volume 1, Issue 2 (2014). Leibniz Transactions on Embedded Systems, Volume 1, Issue 2, pp. 01:1-01:22, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2014)

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@Article{brandenburg:LITES-v001-i002-a001,
  author =	{Brandenburg, Bj\"{o}rn Bernhard},
  title =	{{Blocking Optimality in Distributed Real-Time Locking Protocols}},
  booktitle =	{LITES, Volume 1, Issue 2 (2014)},
  pages =	{01:1--01:22},
  journal =	{Leibniz Transactions on Embedded Systems},
  ISSN =	{2199-2002},
  year =	{2014},
  volume =	{1},
  number =	{2},
  editor =	{Brandenburg, Bj\"{o}rn Bernhard},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LITES-v001-i002-a001},
  doi =		{10.4230/LITES-v001-i002-a001},
  annote =	{Keywords: Distributed multiprocessor real-time systems, Real-time locking, Priority inversion, Blocking optimality}
}
Document
DOI: 10.4230/LIPIcs.APPROX-RANDOM.2014.356
Robust Appointment Scheduling

Authors: Shashi Mittal, Andreas S. Schulz, and Sebastian Stiller

Published in: LIPIcs, Volume 28, Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2014)

Abstract
Health care providers are under tremendous pressure to reduce costs and increase quality of their services. It has long been recognized that well-designed appointment systems have the potential to improve utilization of expensive personnel and medical equipment and to reduce waiting times for patients. In a widely influential survey on outpatient scheduling, Cayirli and Veral (2003) concluded that the "biggest challenge for future research will be to develop easy-to-use heuristics." We analyze the appointment scheduling problem from a robust-optimization perspective, and we establish the existence of a closed-form optimal solution--arguably the simplest and best `heuristic' possible. In case the order of patients is changeable, the robust optimization approach yields a novel formulation of the appointment scheduling problem as that of minimizing a concave function over a supermodular polyhedron. We devise the first constant-factor approximation algorithm for this case.
Cite as

Shashi Mittal, Andreas S. Schulz, and Sebastian Stiller. Robust Appointment Scheduling. In Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2014). Leibniz International Proceedings in Informatics (LIPIcs), Volume 28, pp. 356-370, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2014)

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@InProceedings{mittal_et_al:LIPIcs.APPROX-RANDOM.2014.356,
  author =	{Mittal, Shashi and Schulz, Andreas S. and Stiller, Sebastian},
  title =	{{Robust Appointment Scheduling}},
  booktitle =	{Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2014)},
  pages =	{356--370},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-74-3},
  ISSN =	{1868-8969},
  year =	{2014},
  volume =	{28},
  editor =	{Jansen, Klaus and Rolim, Jos\'{e} and Devanur, Nikhil R. and Moore, Cristopher},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.APPROX-RANDOM.2014.356},
  URN =		{urn:nbn:de:0030-drops-47089},
  doi =		{10.4230/LIPIcs.APPROX-RANDOM.2014.356},
  annote =	{Keywords: Robust Optimization, Health Care Scheduling, Approximation Algorithms}
}
Document
DOI: 10.4230/LIPIcs.STACS.2014.276
Packing a Knapsack of Unknown Capacity

Authors: Yann Disser, Max Klimm, Nicole Megow, and Sebastian Stiller

Published in: LIPIcs, Volume 25, 31st International Symposium on Theoretical Aspects of Computer Science (STACS 2014)

Abstract
We study the problem of packing a knapsack without knowing its capacity. Whenever we attempt to pack an item that does not fit, the item is discarded; if the item fits, we have to include it in the packing. We show that there is always a policy that packs a value within factor 2 of the optimum packing, irrespective of the actual capacity. If all items have unit density, we achieve a factor equal to the golden ratio. Both factors are shown to be best possible. In fact, we obtain the above factors using packing policies that are universal in the sense that they fix a particular order of the items and try to pack the items in this order, independent of the observations made while packing. We give efficient algorithms computing these policies. On the other hand, we show that, for any a>1, the problem of deciding whether a given universal policy achieves a factor of a is coNP-complete. If a is part of the input, the same problem is shown to be coNP-complete for items with unit densities. Finally, we show that it is coNP-hard to decide, for given a, whether a set of items admits a universal policy with factor a, even if all items have unit densities.
Cite as

Yann Disser, Max Klimm, Nicole Megow, and Sebastian Stiller. Packing a Knapsack of Unknown Capacity. In 31st International Symposium on Theoretical Aspects of Computer Science (STACS 2014). Leibniz International Proceedings in Informatics (LIPIcs), Volume 25, pp. 276-287, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2014)

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@InProceedings{disser_et_al:LIPIcs.STACS.2014.276,
  author =	{Disser, Yann and Klimm, Max and Megow, Nicole and Stiller, Sebastian},
  title =	{{Packing a Knapsack of Unknown Capacity}},
  booktitle =	{31st International Symposium on Theoretical Aspects of Computer Science (STACS 2014)},
  pages =	{276--287},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-65-1},
  ISSN =	{1868-8969},
  year =	{2014},
  volume =	{25},
  editor =	{Mayr, Ernst W. and Portier, Natacha},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.STACS.2014.276},
  URN =		{urn:nbn:de:0030-drops-44642},
  doi =		{10.4230/LIPIcs.STACS.2014.276},
  annote =	{Keywords: Knapsack, unknown capacity, robustness, approximation algorithms}
}
Document
Complete Volume
DOI: 10.4230/OASIcs.ATMOS.2013
OASIcs, Volume 33, ATMOS'13, Complete Volume

Authors: Daniele Frigioni and Sebastian Stiller

Published in: OASIcs, Volume 33, 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (2013)

Abstract
OASIcs, Volume 33, ATMOS'13, Complete Volume
Cite as

Daniele Frigioni and Sebastian Stiller. OASIcs, Volume 33, ATMOS'13, Complete Volume. In 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems. Open Access Series in Informatics (OASIcs), Volume 33, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2013)

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@Proceedings{frigioni_et_al:OASIcs.ATMOS.2013,
  title =	{{OASIcs, Volume 33, ATMOS'13, Complete Volume}},
  booktitle =	{13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-58-3},
  ISSN =	{2190-6807},
  year =	{2013},
  volume =	{33},
  editor =	{Frigioni, Daniele and Stiller, Sebastian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2013},
  URN =		{urn:nbn:de:0030-drops-42535},
  doi =		{10.4230/OASIcs.ATMOS.2013},
  annote =	{Keywords: Analysis of Algorithms and Problem Complexity, Optimization, Graph Theory, Applications}
}
Document
Front Matter
DOI: 10.4230/OASIcs.ATMOS.2013.i
Frontmatter, Table of Contents, Preface, Workshop Organization

Authors: Daniele Frigioni and Sebastian Stiller

Published in: OASIcs, Volume 33, 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (2013)

Abstract
Frontmatter, Table of Contents, Preface, Workshop Organization
Cite as

Daniele Frigioni and Sebastian Stiller. Frontmatter, Table of Contents, Preface, Workshop Organization. In 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems. Open Access Series in Informatics (OASIcs), Volume 33, pp. i-xii, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2013)

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@InProceedings{frigioni_et_al:OASIcs.ATMOS.2013.i,
  author =	{Frigioni, Daniele and Stiller, Sebastian},
  title =	{{Frontmatter, Table of Contents, Preface, Workshop Organization}},
  booktitle =	{13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems},
  pages =	{i--xii},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-58-3},
  ISSN =	{2190-6807},
  year =	{2013},
  volume =	{33},
  editor =	{Frigioni, Daniele and Stiller, Sebastian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2013.i},
  URN =		{urn:nbn:de:0030-drops-42391},
  doi =		{10.4230/OASIcs.ATMOS.2013.i},
  annote =	{Keywords: Frontmatter, Table of Contents, Preface, Workshop Organization}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2013.1
Recoverable Robust Timetable Information

Authors: Marc Goerigk, Sacha Heße, Matthias Müller-Hannemann, Marie Schmidt, and Anita Schöbel

Published in: OASIcs, Volume 33, 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (2013)

Abstract
Timetable information is the process of determining a suitable travel route for a passenger. Due to delays in the original timetable, in practice it often happens that the travel route cannot be used as originally planned. For a passenger being already en route, it would hence be useful to know about alternatives that ensure that his/her destination can be reached. In this work we propose a recoverable robust approach to timetable information; i.e., we aim at finding travel routes that can easily be updated when delays occur during the journey. We present polynomial-time algorithms for this problem and evaluate the performance of the routes obtained this way on schedule data of the German train network of 2013 and simulated delay scenarios.
Cite as

Marc Goerigk, Sacha Heße, Matthias Müller-Hannemann, Marie Schmidt, and Anita Schöbel. Recoverable Robust Timetable Information. In 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems. Open Access Series in Informatics (OASIcs), Volume 33, pp. 1-14, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2013)

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@InProceedings{goerigk_et_al:OASIcs.ATMOS.2013.1,
  author =	{Goerigk, Marc and He{\ss}e, Sacha and M\"{u}ller-Hannemann, Matthias and Schmidt, Marie and Sch\"{o}bel, Anita},
  title =	{{Recoverable Robust Timetable Information}},
  booktitle =	{13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems},
  pages =	{1--14},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-58-3},
  ISSN =	{2190-6807},
  year =	{2013},
  volume =	{33},
  editor =	{Frigioni, Daniele and Stiller, Sebastian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2013.1},
  URN =		{urn:nbn:de:0030-drops-42407},
  doi =		{10.4230/OASIcs.ATMOS.2013.1},
  annote =	{Keywords: timetable information, recoverable robustness, delay scenarios}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2013.15
Is Timetabling Routing Always Reliable for Public Transport?

Authors: Donatella Firmani, Giuseppe F. Italiano, Luigi Laura, and Federico Santaroni

Published in: OASIcs, Volume 33, 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (2013)

Abstract
Current route planning algorithms for public transport networks are mostly based on timetable information only, i.e., they compute shortest routes under the assumption that all transit vehicles (e.g., buses, subway trains) will incur in no delays throughout their trips. Unfortunately, unavoidable and unexpected delays often prevent transit vehicles to respect their originally planned schedule. In this paper, we try to measure empirically the quality of the solutions offered by timetabling routing in a real public transport network, where unpredictable delays may happen with a certain frequency, such as the public transport network of the metropolitan area of Rome. To accomplish this task, we take the time estimates required for trips provided by a timetabling-based route planner (such as Google Transit) and compare them against the times taken by the trips according to the actual tracking of transit vehicles in the transport network, measured through the GPS data made available by the transit agency. In our experiments, the movement of transit vehicles was only mildly correlated to the timetable, giving strong evidence that in such a case timetabled routing may fail to deliver optimal or even high-quality solutions.
Cite as

Donatella Firmani, Giuseppe F. Italiano, Luigi Laura, and Federico Santaroni. Is Timetabling Routing Always Reliable for Public Transport?. In 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems. Open Access Series in Informatics (OASIcs), Volume 33, pp. 15-26, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2013)

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@InProceedings{firmani_et_al:OASIcs.ATMOS.2013.15,
  author =	{Firmani, Donatella and Italiano, Giuseppe F. and Laura, Luigi and Santaroni, Federico},
  title =	{{Is Timetabling Routing Always Reliable for Public Transport?}},
  booktitle =	{13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems},
  pages =	{15--26},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-58-3},
  ISSN =	{2190-6807},
  year =	{2013},
  volume =	{33},
  editor =	{Frigioni, Daniele and Stiller, Sebastian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2013.15},
  URN =		{urn:nbn:de:0030-drops-42415},
  doi =		{10.4230/OASIcs.ATMOS.2013.15},
  annote =	{Keywords: Shortest Path Problems, Route Planning, Timetable-based Routing, Public Transport Networks}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2013.27
Robust Routing in Urban Public Transportation: How to Find Reliable Journeys Based on Past Observations

Authors: Katerina Böhmová, Matús Mihalák, Tobias Pröger, Rastislav Srámek, and Peter Widmayer

Published in: OASIcs, Volume 33, 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (2013)

Abstract
We study the problem of robust routing in urban public transportation networks. In order to propose solutions that are robust for typical delays, we assume that we have past observations of real traffic situations available. In particular, we assume that we have "daily records" containing the observed travel times in the whole network for a few past days. We introduce a new concept to express a solution that is feasible in any record of a given public transportation network. We adapt the method of Buhmann et al. [Buhmann et al., ITCS 2013] for optimization under uncertainty, and develop algorithms that allow its application for finding a robust journey from a given source to a given destination. The performance of the algorithms and the quality of the predicted journey are evaluated in a preliminary experimental study. We furthermore introduce a measure of reliability of a given journey, and develop algorithms for its computation. The robust routing concepts presented in this work are suited specially for public transportation networks of large cities that lack clear hierarchical structure and contain services that run with high frequencies.
Cite as

Katerina Böhmová, Matús Mihalák, Tobias Pröger, Rastislav Srámek, and Peter Widmayer. Robust Routing in Urban Public Transportation: How to Find Reliable Journeys Based on Past Observations. In 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems. Open Access Series in Informatics (OASIcs), Volume 33, pp. 27-41, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2013)

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@InProceedings{bohmova_et_al:OASIcs.ATMOS.2013.27,
  author =	{B\"{o}hmov\'{a}, Katerina and Mihal\'{a}k, Mat\'{u}s and Pr\"{o}ger, Tobias and Sr\'{a}mek, Rastislav and Widmayer, Peter},
  title =	{{Robust Routing in Urban Public Transportation: How to Find Reliable Journeys Based on Past Observations}},
  booktitle =	{13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems},
  pages =	{27--41},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-58-3},
  ISSN =	{2190-6807},
  year =	{2013},
  volume =	{33},
  editor =	{Frigioni, Daniele and Stiller, Sebastian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2013.27},
  URN =		{urn:nbn:de:0030-drops-42428},
  doi =		{10.4230/OASIcs.ATMOS.2013.27},
  annote =	{Keywords: Algorithms, Optimization, Robustness, Route planning, Public transportation}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2013.42
Delay-Robustness of Transfer Patterns in Public Transportation Route Planning

Authors: Hannah Bast, Jonas Sternisko, and Sabine Storandt

Published in: OASIcs, Volume 33, 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (2013)

Abstract
Transfer pattern routing is a state-of-the-art speed-up technique for finding optimal paths which minimize multiple cost criteria in public transportation networks. It precomputes sequences of transfer stations along optimal paths. At query time, the optimal paths are searched among the stored transfer patterns, which allows for very fast response times even on very large networks. On the other hand, even a minor change to the timetables may affect many optimal paths, so that, in principle, a new computation of all optimal transfer patterns becomes necessary. In this paper, we examine the robustness of transfer pattern routing towards delay, which is the most common source of such updates. The intuition is that the deviating paths caused by typical updates are already covered by original transfer patterns. We perform experiments which show that the transfer patterns are remarkably robust even to large and many delays, which underlines the applicability and reliability of transfer pattern routing in realistic routing applications.
Cite as

Hannah Bast, Jonas Sternisko, and Sabine Storandt. Delay-Robustness of Transfer Patterns in Public Transportation Route Planning. In 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems. Open Access Series in Informatics (OASIcs), Volume 33, pp. 42-54, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2013)

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@InProceedings{bast_et_al:OASIcs.ATMOS.2013.42,
  author =	{Bast, Hannah and Sternisko, Jonas and Storandt, Sabine},
  title =	{{Delay-Robustness of Transfer Patterns in Public Transportation Route Planning}},
  booktitle =	{13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems},
  pages =	{42--54},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-58-3},
  ISSN =	{2190-6807},
  year =	{2013},
  volume =	{33},
  editor =	{Frigioni, Daniele and Stiller, Sebastian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2013.42},
  URN =		{urn:nbn:de:0030-drops-42434},
  doi =		{10.4230/OASIcs.ATMOS.2013.42},
  annote =	{Keywords: Route planning, public transportation, transfer patterns, delay, robustness}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2013.55
Solving a Freight Railcar Flow Problem Arising in Russia

Authors: Ruslan Sadykov, Alexander A. Lazarev, Vitaliy Shiryaev, and Alexey Stratonnikov

Published in: OASIcs, Volume 33, 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (2013)

Abstract
We consider a variant of the freight railcar flow problem. In this problem, we need 1) to choose a set of transportation demands between stations in a railroad network, and 2) to fulfill these demands by appropriately routing the set of available railcars, while maximizing the total profit. We formulate this problem as a multi-commodity flow problem in a large space-time graph. Three approaches are proposed to solve the Linear Programming relaxation of this formulation: direct solution by an LP solver, a column generation approach based on the path reformulation, and a ``column generation for extended formulations'' approach. In the latter, the multi-commodity flow formulation is solved iteratively by dynamic generation of arc flow variables. Three approaches have been tested on a set of real-life instances provided by one of the largest freight rail transportation companies in Russia. Instances with up to 10 millions of arc flow variables were solved within minutes of computational time.
Cite as

Ruslan Sadykov, Alexander A. Lazarev, Vitaliy Shiryaev, and Alexey Stratonnikov. Solving a Freight Railcar Flow Problem Arising in Russia. In 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems. Open Access Series in Informatics (OASIcs), Volume 33, pp. 55-67, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2013)

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@InProceedings{sadykov_et_al:OASIcs.ATMOS.2013.55,
  author =	{Sadykov, Ruslan and Lazarev, Alexander A. and Shiryaev, Vitaliy and Stratonnikov, Alexey},
  title =	{{Solving a Freight Railcar Flow Problem Arising in Russia}},
  booktitle =	{13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems},
  pages =	{55--67},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-58-3},
  ISSN =	{2190-6807},
  year =	{2013},
  volume =	{33},
  editor =	{Frigioni, Daniele and Stiller, Sebastian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2013.55},
  URN =		{urn:nbn:de:0030-drops-42448},
  doi =		{10.4230/OASIcs.ATMOS.2013.55},
  annote =	{Keywords: Freight routing, multi-commodity flow, column generation}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2013.68
A Configuration Model for the Line Planning Problem

Authors: Ralf Borndörfer, Heide Hoppmann, and Marika Karbstein

Published in: OASIcs, Volume 33, 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (2013)

Abstract
We propose a novel extended formulation for the line planning problem in public transport. It is based on a new concept of frequency configurations that account for all possible options to provide a required transportation capacity on an infrastructure edge. We show that this model yields a strong LP relaxation. It implies, in particular, general classes of facet defining inequalities for the standard model.
Cite as

Ralf Borndörfer, Heide Hoppmann, and Marika Karbstein. A Configuration Model for the Line Planning Problem. In 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems. Open Access Series in Informatics (OASIcs), Volume 33, pp. 68-79, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2013)

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@InProceedings{borndorfer_et_al:OASIcs.ATMOS.2013.68,
  author =	{Bornd\"{o}rfer, Ralf and Hoppmann, Heide and Karbstein, Marika},
  title =	{{A Configuration Model for the Line Planning Problem}},
  booktitle =	{13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems},
  pages =	{68--79},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-58-3},
  ISSN =	{2190-6807},
  year =	{2013},
  volume =	{33},
  editor =	{Frigioni, Daniele and Stiller, Sebastian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2013.68},
  URN =		{urn:nbn:de:0030-drops-42451},
  doi =		{10.4230/OASIcs.ATMOS.2013.68},
  annote =	{Keywords: Combinatorial optimization, polyhedral combinatorics, line planning}
}
Document
DOI: 10.4230/OASIcs.ATMOS.2013.80
The Stop Location Problem with Realistic Traveling Time

Authors: Emilio Carrizosa, Jonas Harbering, and Anita Schöbel

Published in: OASIcs, Volume 33, 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (2013)

Abstract
In this paper we consider the location of stops along the edges of an already existing public transportation network. This can be the introduction of bus stops along some given bus routes, or of railway stations along the tracks in a railway network. The positive effect of new stops is given by the better access of the customers to the public transport network, while the traveling time increases due to the additional stopping activities of the trains which is a negative effect for the customers. Our goal is to locate new stops minimizing a realistic traveling time which takes acceleration and deceleration of the vehicles into account. We distinguish two variants: in the first (academic) version we locate $p$ stops, in the second (real-world applicable) version the goal is to cover all demand points with a minimal amount of realistic traveling time. As in other works on stop location, covering may be defined with respect to an arbitrary norm. For the first version, we present a polynomial approach while the latter version is NP-hard. We derive a finite candidate set and an IP formulation. We discuss the differences to the model neglecting the realistic traveling time and provide a case study showing that our procedures are applicable in practice and do save in average more than 3% of traveling time for the passengers.
Cite as

Emilio Carrizosa, Jonas Harbering, and Anita Schöbel. The Stop Location Problem with Realistic Traveling Time. In 13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems. Open Access Series in Informatics (OASIcs), Volume 33, pp. 80-93, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2013)

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@InProceedings{carrizosa_et_al:OASIcs.ATMOS.2013.80,
  author =	{Carrizosa, Emilio and Harbering, Jonas and Sch\"{o}bel, Anita},
  title =	{{The Stop Location Problem with Realistic Traveling Time}},
  booktitle =	{13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems},
  pages =	{80--93},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-939897-58-3},
  ISSN =	{2190-6807},
  year =	{2013},
  volume =	{33},
  editor =	{Frigioni, Daniele and Stiller, Sebastian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2013.80},
  URN =		{urn:nbn:de:0030-drops-42467},
  doi =		{10.4230/OASIcs.ATMOS.2013.80},
  annote =	{Keywords: Stop Location, Realistic Traveling Time, IP Formulation}
}
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